Make GrGLShaderBuilder check whether GrEffect advertised that it would require the dst color or frag

src/gpu/gl/GrGLProgramDesc.cpp

 /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "GrGLProgramDesc.h"
 #include "GrBackendEffectFactory.h"
 #include "GrDrawEffect.h"
@@ skipping 69 matching lines @@
 
     for (int s = 0; s < GrDrawState::kNumStages; ++s) {
 
         bool skip = s < drawState.getFirstCoverageStage() ? skipColor : skipCoverage;
         if (!skip && drawState.isStageEnabled(s)) {
             lastEnabledStage = s;
             const GrEffectRef& effect = *drawState.getStage(s).getEffect();
             const GrBackendEffectFactory& factory = effect->getFactory();
             GrDrawEffect drawEffect(drawState.getStage(s), requiresLocalCoordAttrib);
             desc->fEffectKeys[s] = factory.glEffectKey(drawEffect, gpu->glCaps());
-            if (effect->willReadDst()) {
+            if (effect->willReadDstColor()) {
                 readsDst = true;
             }
         } else {
             desc->fEffectKeys[s] = 0;
         }
     }
 
     if (readsDst) {
         GrAssert(NULL != dstCopy || gpu->caps()->dstReadInShaderSupport());
         const GrTexture* dstCopyTexture = NULL;
@@ skipping 90 matching lines @@
 
     if (requiresCoverageAttrib) {
         desc->fCoverageAttributeIndex = drawState.coverageVertexAttributeIndex();
     } else if (GrGLProgramDesc::kAttribute_ColorInput == desc->fCoverageInput) {
         GrAssert(availableAttributeIndex < GrDrawState::kMaxVertexAttribCnt);
         desc->fCoverageAttributeIndex = availableAttributeIndex;
     } else {
         desc->fCoverageAttributeIndex = -1;
     }
 }